How to correctly calculate combined shipping rates for different items?

Payments + Shipping & Fulfilment

Topic summary

Main issue: Two shipping profiles from the same origin—small items with a $1 flat rate and other items using USPS Ground Advantage (calculated by weight).

Observed behavior: Each profile prices correctly on its own. In mixed carts, Shopify combines rates, charging $1 + the calculated USPS cost.

Requested outcome: When small and large items are purchased together, charge only the calculated USPS rate (effectively making the small items ship free within the same parcel).

Current answer: Not possible with multiple shipping profiles. Shopify’s system combines rates across profiles in a single order, resulting in summed shipping charges. An official help article on combined shipping rates is referenced.

Status: Unresolved within current platform capabilities; no workaround provided in the discussion. The request cannot be achieved without changing the shipping profile setup or platform behavior.

Summarized with AI on January 2. AI used: gpt-5.
1

Here’s the setup:
I have some small items that cost $1 to ship. I have other items that ship based on USPS ground advantage shipping rates. Each use different shipping profiles but ship from the same place.

Here’s the issue:
If someone adds one of those smaller items to their cart, the shipping is calculated correctly – $1.
If someone adds any number of other items, the shipping is calculated correctly based on weight.
However if someone orders one of those smaller items and one of the other items, the shipping rates combine: $1+ calculated shipping cost.

What I’m looking for:
If someone orders the smaller item with the other items I would just like to use the calculated shipping cost of the other items because they would be packaged in the same parcel. Essentially shipping would be free on those smaller items if their paired with larger ones.

2

This is not possible. If you have multiple shipping profiles, then the shipping rates will be combined